A variety of diagnostic and therapeutic procedures involve the introduction of a device through a natural or artificially created access pathway. A general objective of access systems, which have been developed for this purpose, is to minimize the cross-sectional area of the puncture and pathway, while maximizing the available space for the diagnostic or therapeutic instrument.
A percutaneous introducer sheath can be used to access the vascular system of a patient to introduce and position various transcatheter medical devices within the patient. The introducer sheath is a tube-like member which is partially inserted into the vasculature at a puncture site while the proximal, or working end, of the introducer sheath remains outside of the vasculature for accessibility to introduce a transcatheter medical device through the sheath. A guide wire can be inserted through the introducer sheath and subsequently steered through the vascular system to the site of therapy.
Large-profile transcatheter medical devices have traditionally required a larger-profile introducer sheath which provides a fixed internal clearance to allow the device to pass through the patient's vasculature. Such procedures using the large-profile transcatheter medical devices, typically through the femoral artery, are therefore limited to patients with sufficient vessel size to accommodate the introducer sheath. In order to extend the availability of large-profile transcatheter devices to patients with smaller vessel sizes, an introducer with a smaller profile that locally expands within the patient's vasculature to allow passage of the large-profile transcatheter device is desired.